1. Field of the Invention
The present invention generally relates to in multi-access points of a wireless LAN (Local Area Network) system, and more specifically to an apparatus for controlling load balance of multi-access points in a wireless LAN system and a method thereof for preventing load from being concentrated on a specific access point by comparatively evaluating load values of many access points after receiving the load values of the access points, and rejecting terminal access or removing existing accessed terminals in an access point where load is concentrated.
2. Description of the Related Art
Generally, widely-used information terminals such as PCs (Personal Computers) or notebooks, PDAs (Personal Digital Assistants) configure a network named LAN (Local Area Network) to reciprocally share information. The LAN is divided into a wired LAN configured by directly connecting the information terminals with the use of communication cables and a wireless LAN configured in wireless communication way using access points.
The wireless LAN is free to move by transceiving data in the wireless communication way with the use of RF (Radio Frequency) or light, as well as easy to expand and maintain. In addition, it supplies a 10/100 BASE-T Ethernet interface function of IEEE (Institute of Electrical and Electronics Engineers) 802.3 as a wired processor, and secures a 2 Mbps (megabits per second) transmission rate in a 2.4 GHz (gigahertz) frequency band of IEEE 802.11 as a wireless processor.
A wireless LAN system configures a network including: a wireless LAN terminal, an information terminal used by a wireless LAN user; a router and a hub for Internet access; an authenticating server providing an Internet access service; and an access point located between the wireless LAN terminal and the hub relays wireless LAN communication of the corresponding wireless LAN terminal by transmitting an Internet access request to the authenticating server.
Here, the access point is a wireless LAN access equipment supporting interworking between an existing wired LAN service area and a wireless LAN service area, and includes more than one Ethernet MAC (Media Access Control) and wireless LAN MAC. According to a definition of the wireless LAN MAC in the IEEE 802.11, the access point passes through authentication and association processes in order to manage a self wireless LAN service area.
In other words, while requesting Internet access of the wireless LAN terminal, the existing access point performs a wireless LAN relaying function to access the Internet by requesting access authentication of the authenticating server after receiving Internet access information, that is, IP (Internet protocol), gateway, and DNS (Domain Name Server) information preset in the wireless LAN terminal from the corresponding wireless LAN terminal.
At this time, the wireless LAN terminal is authenticated from the authenticating server to access the Internet by inputting a self registered member ID (Identifier) and a password. If the authenticating server permits the Internet access, the corresponding wireless LAN terminal configures a wireless network by having access to the Internet through the access point, the hub, and the router, and transceives data over the Internet. If the authenticating server rejects the Internet access, the Internet access is prohibited.
In the meantime, in order to carry out a roaming process (here, this means communication connection switching is performed from one access point to other access point) to another access point from one access point, the wireless LAN terminal executes an operation (scanning) of finding out an access point in which the wireless LAN terminal can register, after transmitting a probe request frame and receiving a probe response frame.
Common scans include two types of scans, that is, an active mode scan and a passive mode scan in a default state. First, the active mode scan is performed, and if the access point is not found within a BSS (Basic Service Set), a scanning mode is switched into the passive mode scan to perform the passive mode scan. If the access point is not still found, the active mode scan and the passive mode scan are repeated.
In the above operation (scanning operation), all channels should be scanned to find out an accessible access point. The roaming process is carried out when the wireless LAN terminal transmits an authentication request frame (requesting the wireless LAN terminal to register in the access point (IEEE802.11)) to an initially-accessed access point based on the scans and receives an authentication response frame authenticating the wireless LAN terminal from the access point.
However, according to the above roaming system, the wireless LAN terminal is separated from a current access point, scans all accessible access points, and performs a registration procedure in an access point having a maximum RSSI (Receive Signal Structure Indicator).
Meanwhile, according to an earlier art in which the wireless LAN terminal attempts to access the access point and maintains the access by using an RSSI in a wireless LAN, there is a problem that load is concentrated on several access points while using multi-access points.
In a wireless LAN environment having multi-access points, the wireless LAN terminals are concentrated on an access point by being located in the access point. On the contrary, there occurs an unequal situation, for instance, an access point does not have any wireless LAN terminals.
Thus, the wireless LAN terminals of the wireless LAN try to access a near access point. In case the access point permits the access of the terminals, if signal strength of the access point satisfies a threshold value determined in the wireless LAN terminals although load is concentrated on the access point, the wireless LAN terminals continuously maintain data communication through the access point having much load even though other access point is in an idle state. As a result, the wireless LAN operating the multi-access points is inefficiently performed and the access point having the concentrated load causes delay and error problems.